Pilot operated servo valve



March 15, 1949. A. P. WATERsoN PILOT OPERATED SERVO VALVE Fiied on. 22, 1947 2 Sheets-Sheet 1 INVENTOR. AR THUR P. WA TE RSO A TTORNEYS.

March 15, 1949. A. P. WATERSQN 2,464,626

PILOT OPERATED SERVO VALVE Filed Oct. 22, 1947 2 Sheets-Sheet'Z r Y" a. A 77' OFNE 78 N w m. 3 mm. TT .F 7 m a V N d I L I l 5 m at |$|l NW 1 M 2 I1 v v 8 m2 5 m+ 9 o a 8 8 m 0E 3 2. m m c r .Xmg mm 8 1 mm 4 IHIIIPU- m n I n on v wnlhl E m s 5 2. MM H 1W WWW u a L m m om m HM 'rTN rm 3 1 mv em+ m mm v P. QM

Patented Mar. 15, 1949 'UNITED sTA'ras PATENT OFFICE PILOT OPERATED SERVO VALVE Arthur P. Water-son, Tulsa, Okla assignor to The R. K. Le Blond Machine Tool Company, Cincinnati, Ohio, a corporation of Delaware Application October 22, 1947, Serial No. 781,436

9 Claims. (Cl. 121-45) Still another object of this invention is to provide a pilot operated servo valve which may be readily set for the desired degree of accuracy and the desired size of actuating cylinder to be used therewith in controlling the movements of a machine member.

Further features and advantages of this invention will appear from a detailed description of the drawings in which:

Figure l is a side elevation of a typical tracer control duplicating attachment to which this invention is particularly well adapted.

Figure 2 is a front end view of the attachment of Figure 1 indicated by the line 22 of Figure 1.

Figure 3 is a diagrammatic section of the hydraulic valve system indicated by the line 3-3 in Figure 2.

Figure 4 is an exploded side view of the series of outside valve port forming collars shown in Figure 3.

Figure 5 is avsimilar view to Figure 4 of the mating inside set of port forming collars for the valve mechanism.

Figure 6 is an enlarged sectional view through the pilot valve on the line 6-6 of Figure 3.

Figure 7 is a perspective view of one of the port forming collars of the pilot valve.

For exemplary purposes, this invention is shown applied to a duplicating attachment adapted to be used with a machine toolsuch as an engine lathe having a cross slide l0 upon which is mount- L ed the duplicator attachment swivel base II by the usual mounting screws l2, commonly used in connection with lathes. On suitable guideways I la formed in the swivel base I I is mounted to slide to and from the work, the tool slide l3 having the usual tool post l4 and cutting tool I! as commonly used in a lathe.

The tool slide is reciprocated in tracer controlled movements on the swivel base I I by means of a fluid pressure cylinder l6 rigidly fixed to the tool slide l3 by suitable means and having a piston l1 and piston rod [8 connected through a suitable bracket l9 bolted to the swivel base II by suitable screws 20 so that upon application of fluid pressure in the cylinder l6 the tool slide l3 gray ilile relatively reciprocated on the swivel ase A source of fluid pressure is provided by a fluid pressure pump 2| which receives a supply of fluid through a suction line 22 from the fluid reservoir and delivers fluid under pressure to the pressure supply line 24 in which is connected at pressure relief valve 25 discharging through a drain line 26 into the fluid reservoir 23 to maintain a predetermined desired operating pressure in the pressure supplyline 24. The pressure supply line 24 is connected to the pressure supply passageway 21 in the supply spindle 28 of the main four-way reversing control valve indicated generally at 29 which valve 29-may preferably be of a type such as shown in applicants copending applications Serial No..675,523, filed June 10, 1946, and Serial No. 743,669, flled April 24, 1947. Since the details of construction of the main control valve 29 form no specific part of applicants instant invention, it is suflicient to state that there is provided a valve stem 36 which is rigidly fixed to the tool slide l3 and has provided thereon a series of inner port forming collars 3 I, 32, 33, 34, and 35 which cooperate with mating port forming collars 36, 31, 38, 39, and 40 carried in the movable control sleeve 4! so as to provide intake ports 44 connected to the annular groove 42 formed in the spindle 28 which is in communication with the passageway 21 through the radial passageways 43 formed in the stem 28. Exhaust ports 45 opening through passageways 45a into the sump chamber 451: are also provided by the port forming collars. A return line 45c conveys exhausted fluid back to the reservoir 23. An intake and exhaust port 44 and 45 are each connected to a line 46 going to the chamber 41 of the cylinder 16 while the other intake and exhaust port of the valve 29 is connected through a line 48 to the chamber 49 of the cylinder I'B in such a way that with pressure being applied through the line 24 reciprocation of the valve sleeve 4| relative to the spindle 36 and its port forming collars 3| to 35, inclusive, provides a means for reversibly controlling and positioning accurately the piston I1 and cylinder l6 and therefore the tool slide l3 relative to the work piece to the lathe carriage.

The control valve sleeve 4| of the valve 29 is controlled from pilot valve indicated generally at 50. This pilot valve is provided with a rotatable 3 valve stem H which is iournaled in a bearing 52 in the tool slide I3 and isguided against axial movement by the shoulder 53 of the valve stem and an adjustable collar 54 locked in adjusted position by a suitable set screw 55. This stem 5I is provided with a screw driver slot 58 or any other suitable means by which the stem may be rotated to a series of positions 58a such as shown in Figure 2. On the stem 5| is provided a series of port forming collars 51, 58, 59, 88, and 8i each locked in place against the other by means of an abutment collar 82 which is engaged by a closure plug 83 threaded at 84 into a cylinder bore 85 provided in the spindle 5|. In the cylinder bore 85 is provided a piston 88 having a con- 89 and 18 iormedbetween the respective collars 8|, 82, and 83.

The pilot valve sleeve 88 may be actuated in erally at I8I so as to relatively reciprocate the nectin rod 81 passing through a suitable guide bore in the plug 83 and bolted by suitable nut means 88 to a projecting arm 4Ia of the valve sleeve 4| of the valve 29 so that reciprocation of piston 88 by fluid pressure in the cylinder bore 85 eiiects adjustment of the sleeve H of the valve 29. Each of the inner port forming collars 51 to 8|, inclusive, is formed as shown in Figure 5 so as to provide intake ports 89 and I8 and exhaust ports II and I2. Port 89 is in communication with the chamber I3 of the cylinder bore 85 through a passageway 14 while the exhaust port II is in communication through a passageway I5 with the chamber I3. Intake port I8 communicates through a passageway I8 with a chamber I! in the cylinder 85 while exhaust port I2 communicates through a passageway 18 with .the chamber 11 of the cylinder 85.

Each of the intake ports 59 and I8 and exhaust ports II and I2 is formed as narrow segmental peripheral slits formed by raised portions such as I9 provided on the collar members 58 and 88 and these raised portions I9 are of segmental character covering 90 degree arcuate portions, as best seen in Figure 6, around the periphery of the respective port formin collars.

Around the outside of the port forming collars 51 to 8 I, inclusive, just described, is a mating setof outside port forming collars 88, 8I, 82, 83, and 84 as shown in detail in Figure 4. The collars 88, 82, and 84 are provided with segmental raised portions 85 located to cover 98 degree arcuate portions as best shown in Figure 8, forming slitted openings cooperating with the slits formed by the inner collars to form the ports 89, I8, II, and 12. All of the port forming collars 88 to 84, inclusive, are locked securely to the pilot valve sleeve 88 by a suitable threaded clamping collar 81 securely binding all of these port forming collars against the shoulder 88 of the sleeve 88.

g In Figure 'l is clearly shown the construction of one of the port forming collars, such as the collar 82, having the arcuate segmental raised portions 85 formed thereon and having the cut away portions 89 provided to form the port in conjunction with the mating port forming collars 51 to 8|, inclusive.

Fluid pressure is supplied to the intake ports 89 and I8 through the collars 8|. 82, and 83 from the pressure supply line 98 suitably connected to the pressure supply line 24 as by connection with the pressure passageway 21 in the spindle 28. The line 98 is connected to the passageway 9| formed in a pressure supply spindle 92 for the pilot valve 58, this spindle nicely sliding in a suitable bore 93 formed in the pilot valve sleeve 88. An annular groove'94 communicating through radial passageways 95 with the pressure supply passageway 9I conducts fluid through passageways 98 in the valve sleeve 88 to the intake ports stylus tip 98 in conformity with the pattern I88 over which the tracer is caused to be traversed by the usual feeding movement of the lathe carriage. The tracer finger 91 has an abutment surface I82 engagin an actuating pin I83 fixed to the sleeve 88 of the pilot tracer valve 58 and a bias spring I84 engaging the enlarged head portion of the actuating pin I83 serves to normally move the tracer finger tip 99 toward the template and to bias the pilot valve sleeve 88 in a position to cause normal infeed movement of the cutting tool I5 toward the work piece in the machine.

Thus, in this way, actuation of the tracer finger 91 by the template I88 reciprocates the pilot valve sleeve 88 to vary the flow of fiuid pressure to the chambers I3 and TI of the cylinder bore to cause the piston 88 therein to similarly move the sleeve M of the main control valve 29 which in turn controls the position of the piston I1 and the cylinder I8 for accurately positioning the tool slide I3 in tracer controlled motion. By this arrangement, maximum pressures and high volumes of flow may be readily handled through the main control valve 29 while the pilot tracer control valve 58 may be used to control the valve 29 while requirin a very light sensitive pressure of the tracer finger tip 99 on the template I88.

An important feature of the pilot valve 58 is that its porting may be varied to suit desired operating conditions of responsiveness and sensitlveness to control for different classes and types of work and for different sizes of cylinders to be operated by it. This is accomplished by rotating the valve stem 5| relative to the sleeve 88 by placing a screw driver in the slot 58 and turning the stem and its port forming collars 51, 58, 59, 88, and 8| fixed thereto to diflerent relative peripheral positions with respect to the outer port forming collars 88, 8|, 82, 83, and 84 so as to vary the size of the port openings between the two sets of port forming collars. This can best be seen 'by referring to Figure 6 in which there is shown the relative position of the valve stem 5| in a half-open position in which half of the areas of the ports formed by the collars is in operation. By turning the stem to the full opened position I shown in Figure 2, the maximum porting can be utilized for rapid control and maximum movements under the tracer control action of the template operating against a tracer finger tip. However, when it is desired to have a very minimum of movement and sensitlveness to the apparatus or alight cutting tool slide is being controlled, the valve porting may be turned to a position approaching the closed position 4, Figure 2, so as to in this way give a, greater degree of sensitlveness and quickness of response to the control mechanism ior operating the valve sleeve H in the valve 29 of the pilot valve 58.

There has thus been provided a pilot operated servo valve mechanism in which a primary valve for reversibly controlling the position of a machine member actuated by a fluid pressure cyloneness lnder is controlled by a pilot servo 'valve'which is actuated directly from the template actuated stylus of the tracer mechanism. There has also been provided in a pilot valve controlled servo valve mechanism a means for varying the port openings to any desired value to vary the sensitiveness and rate of response oi! the pilot valve in controlling the main valve of the apparatus to meet all types of operating conditions.

While the apparatus herein disclosed and described constitutes a preferred form at theinvention, it is to be understoodthat the apparatus is capable of mechanical alteration without departing from the spirit of the invention and that such mechanical arrangements and commercial adaptations as fall within thescope of the ap-' pendant claims are intended to be included herein. Having thus fully set forth and described this invention, what is claimed as new and desired to be secured by United States Letters Patent is:

1. In a pilot operated servo valve systemhaving a primary valve, means connecting said valve ports in said pllot valve to eifect reversible and positional control of said valve sleeve of said main valve. 1 I

2. In a pilot operated servo valve system having a primary valve, means connecting said valve to a fluid pressure motor adapted to actuate the machine element, intake and exhaust ports in said main valve and an adjustable sleeve associated with said valve movable to regulate said ports to vary the direction and position of movement of said fluid pressure motor, fluid pressure means for actuating said main valve sleeve including a piston and cylinder arrangement in corporated in a, pilot valve having a stem, ports in said stem communicating with the chambers of said fluid pressure actuating cylinder, an adjustable pilot valve sleeve having movement to vary the openings of the ports in said pilot valve to eflect reversible and positional control of said valve sleeve ofsaid main valve, and means for rotatably adjusting said pilot valve stem relative to said pilot valve sleeve to vary the openings of said ports between said stem and sleeve for varying the rate of response of said fluid pressure actuating cylinder to the actuation of said pilot valve sleeve.

3.'In a pilot operated servo valve system having a primary valve, means connecting said valve to a fluid pressure motor adapted to actuate the machine element, intake and exhaust ports in said main valve and an adjustable sleeve associated with said valve movable to regulate said ports to vary the direction and position of movement of said fluid pressure motor, fluid pressure means for actuating said main valve sleeve including a piston andcylinder arrangement incorporated in a pilot valve having a stem, ports in said stem communicating with the chambers of said fluid pressure actuating cylinder, an adjustable pilot valve sleeve having movement to varythe' openings of the ports in said pilot valve to effect reversible and positional control of said fluid pressure actuating cylinder tor similarly controlling the valve sleeve of said main valve, means for relatively rotatably adjusting said pilot valve'stem and said pilot valve sleeve to vary the openings of said ports between said stem and sleeve for varying the rate of response of said fluid pressure actuating cylinder to the actuation of said pilot valve sleeve, and tracer flnger control means operably engaging a template for regulating the position of said pilot valve sleeve to efiect a template controlled operation of said fluid pressure motor. 4. In a pilot controlled servo valve system, adapted to actuate a fluid pressure motor, a main valve stem connected to each side of said fluid pressure motor, an adjustable valve sleeve axially slldable on said valve stem in ported relationship therewith, and fluid pressure means connected to said valve sleeve for reversibly and variably applying fluid pressurefrom a source thereof to control the operation of said-motor cylinder, a pilot valve having a valve stem, a valve sleeve axially slldable on said valve stem having ported inter connection therewith, a source of fluid pressure connected into said sleeve, and a fluid pressure cylinder controlled by-said flow through said pilot valve, and means connecting said second mentioned fluid \pressure cylinder to actuate the valve sleeve of said main valve. 7

5. In a pilot controlled servo valve system, adapted to actuate a fluid pressure motor, a main valve stem connected to each side of said fluid pressure motor, an adjustable valve sleeve axially slldable on said valve stem in ported relationship therewith, and fluid pressure means connected to said valve sleeve for reversibly and variably applying fluid pressure from asource thereof to control the operation of said motor cylinder, a pilot valve having a valve stem, a valve sleeve axially slldable on said valve stem having ported inner relationship therewith, a sourceof fluid pressure connected into said sleeve, and a fluid pressure cylinder controlled by said flow through said pilot valve, means connecting said second mentioned fluid pressure cylinder to actuate the valve sleeve of said main valve, and means for relatively rotatably adjusting said pilot valve stem relative to said sleeve to change the port openings of said valve to vary the rate of flow of fluid pressure to said second mentioned cylinder for actuating the main valve sleeve.

6. Ina pilot operated servo mechanism for a duplicator attachment for lathe having an actuating cylinder with a reciprocatable piston rod therein, a main control valve having a valve stem with ports formed thereon, a control sleeve for said valve axially slldable on said valve stem having mating ports therein, means for applying fluid pressure to said sleeve to cause controlled pressure flowthrough said porting between said valve sleeve and said valve stem, and means for connecting fluid pressure from the ports in said valve stem to said cylinder, a pilot valve associated with said first mentioned valve comprising a rotatable valve stem having ported means therein, a pilot valve sleeve slldable axially on said valve stem having associated porting therein, means for connecting fluid pressure to said valve sleeve and said ports, and a control cylinder so that'relative adjustment of said pilot valve sleeve eflects similar adjustment of the valve sleeve of said first mentioned valve to control the operation of the piston rod of said cylinder for actuating said tool slide.

7. In a pilot operated servo mechanism for duplicator attachment for lathe having an actuating cylinder a reciprocatable piston rod therein, a main control valve having a valve stem with ports formed thereon, a reciprocatable control sleeve for said valve axially slidable on said valve stem having mating ports therein, means for applying fluid pressure to said sleeve to cause controlled pressure flow through said porting between said valve sleeve and said valve stem, and means for connecting fluid pressure from the ports in said valve stem to said cylinder, a pilot valve associated with said first mentioned valve comprising a rotatable valve stem having ported means therein, a pilot valve sleeve slidable axially on said valve stem having associated porting therein, means for connecting fluid pressure to said valve sleeve and said ports, and a control cylinder connected to said pilot valve by fluid pressure conducting means and mechanically connected to said valve sleeve of said first mentioned valve so that relative adjustment oi said pilot valve sleeve effects similar adjustment of the valve sleeve of said first mentioned valve to control the operation of said piston rod in said cylinder, and tracer finger actuating means for the valve sleeve of said pilot valve.

8. In a pilot operated servomechanism for duplicator attachment for lathe having an actuating cylinder with a piston rod reciproca'table therein, a main control valve having a valve stem with ports formed thereon, a control sleeve for said valve axially slidable on said valve stem having mating ports therein, means for applying fluid pressure to said sleeve to cause controlled pressure flow through said porting between said valve sleeve and said valve stem, and means for connecting fluid pressure from the ports in said valve stem to said cylinder, a pilot valve associated with said first mentioned rotatable valve comprising a valve stem having ported means therein, a pilot valve sleeve slidably axially on said valve stem having associated porting therein, means for connecting fluid pressure to said valve sleeve and said ports, and a control cylinder connected to said pilot valve by fluid pressure conducting means and mechanically connected to said valve sleeve of said first mentioned valve so that relative adjustment of said pilot valve sleeve eifects similar adjustment of the valve sleeve of said first mentioned valve to control the operation of the piston rod in said cylinder, and tracer finger actuating means for the valve sleeve of said pilot valve, said control cylinder being incorporated in said valve stem of said pilot valve and connected directly to the porting of said valve through said valve stem.

9. In a pilot operated servo mechanism for duplicator attachment for lathe having an actuating cylinder with a piston 'rod reciprocatable thereima main control valve having a valve stem with ports formed thereon, a control sleeve for said-valve axially slidable on said valve stem having mating ports therein, means for applying fluid pressure to said sleeve to cause controlled pressure flow through said porting between said valve sleeve and said valve stem, and means for connecting fluid pressure from the ports in said valve stem to said cylinder, a pilot valve associated with said first mentioned valve comprising a rotatable valve stem having ported means therein, 'a pilot valve sleeve slidably axiallyon said valve stem having associated porting therein, means for connecting fluid'pressure to said valve sleeve and said ports, and a control cylinder connected to said pilot valve by fluid pressure conducting means and mechanically connected to said valve sleeve of said first men.- tioned valve so that relative adjustment of said pilot valve sleeve eflects similar adjustment of the valve sleeve of said first mentioned valve to control the operation the piston rod of saidcylinder, and tracer finger actuating means for the valve sleeve of said pilot valve, said control cylinder being incorporated in said valve stem of said pilot valve and connected. directly to the porting ,in said valve stem, and means for rotating saidpilot valve stem relative to said sleeve to vary the size of the porting between said stem and said sleeve of said pilot for varying the rate of flow to said, control cylinder.

" ARTHUR P. WATERSON.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS 

